Preserve the .debug_gdb_scripts section

Make sure that compiler and linker don't optimize the section's contents
away by adding the global holding the data to "llvm.used". The volatile
load in the main shim is retained because "llvm.used", which translates
to SHF_GNU_RETAIN on ELF targets, requires a reasonably recent linker;
emitting the volatile load ensures compatibility with older linkers, at
least when libstd is used.

Pretty printers in dylib dependencies are now emitted by the main crate
instead of the dylib; apart from matching how rlibs are handled, this
approach has the advantage that `omit_gdb_pretty_printer_section` keeps
working with dylib dependencies.

1 files changed, 6 insertions, 6 deletions

diff --git a/compiler/rustc_codegen_llvm/src/base.rs b/compiler/rustc_codegen_llvm/src/base.rs
index 5dda836988c..d7da03bf490 100644
--- a/compiler/rustc_codegen_llvm/src/base.rs
+++ b/compiler/rustc_codegen_llvm/src/base.rs
@@ -109,11 +109,16 @@ pub(crate) fn compile_codegen_unit(
             }
 
             // Finalize code coverage by injecting the coverage map. Note, the coverage map will
-            // also be added to the `llvm.compiler.used` variable, created next.
+            // also be added to the `llvm.compiler.used` variable, created below.
             if cx.sess().instrument_coverage() {
                 cx.coverageinfo_finalize();
             }
 
+            // Finalize debuginfo. This adds to `llvm.used`, created below.
+            if cx.sess().opts.debuginfo != DebugInfo::None {
+                cx.debuginfo_finalize();
+            }
+
             // Create the llvm.used and llvm.compiler.used variables.
             if !cx.used_statics.is_empty() {
                 cx.create_used_variable_impl(c"llvm.used", &cx.used_statics);
@@ -130,11 +135,6 @@ pub(crate) fn compile_codegen_unit(
                     llvm::LLVMDeleteGlobal(old_g);
                 }
             }
-
-            // Finalize debuginfo
-            if cx.sess().opts.debuginfo != DebugInfo::None {
-                cx.debuginfo_finalize();
-            }
         }
 
         ModuleCodegen::new_regular(cgu_name.to_string(), llvm_module)